We really don't know a lot about The Last Guardian. Despite the incredibly long development time, all we really know is it is about a boy and Trico the bird dog. We know nothing of the story, the enemies we'll be fighting or the world the game will take place in.
I thought we might have seen these details expanded on at either of Sony's Press Conferences at TGS or Paris Games Week, but alas, t'was not to be. This is on purpose though. President of Sony Entertainment Shuhei Yoshida told GameSpot that everyone is currently trying to protect the game's narrative.
Development is going well, but because it's about the story, we don't want to show too much. We wanted to show that it exists, it works, it runs. It's not like we won't show anything before launch, but I think we will try to limit what we show about the game.
This leads me to believe that the game might well decide to skip PlayStation Experience next month, in favour of E3 next year. That's a little sad if the case, as I'd like to know more, but I can wait. We've done plenty of that on this title.